1. Field of the Invention
The present invention relates generally to fluid mixing and delivery systems. More particularly, the invention concerns an apparatus for intermixing selected medicaments to form a flowable substance and for then infusing the substance into a patient at a precisely controlled rate.
2. Discussion of the Invention
Medicament delivering systems that can separately store and then controllably intermix a selected medicament with a diluent for infusion into a patient at a controlled rate have come into wide use. In the prior art systems the diluent is generally packaged in flexible plastic containers having administration ports for connection to an administration set which delivers the container contents from the container to the patient. The drug is often packaged in a separate, closed container and is mixed with the diluent shortly before infusion of the medicament in the patient.
Drugs are typically packaged separately from the diluent for a number of reasons. One important reason is that certain drugs do not retain their efficacy when mixed with a diluent and, therefore, the mixture cannot be stored for any appreciable length of time. Another reason is that many drug manufacturers do not produce medical fluids in containers for intravenous delivery. As a general rule, drugs are packaged in powder form in small, closed containers, or vials, for later mixing with a suitable diluent. In many instances it is necessary to mix the drug with the diluent immediately prior to delivery to the patient to insure that the drug will not separate from the diluent prior to or during infusion.
Infusion of medicaments is most often accomplished in a hospital environment and the nurse, doctor or other medical personnel mixes the drug and diluent shortly before administration of the drug to the patient. This mixing step can be time consuming and hazardous, as for example, when toxic drugs are used. Additionally, many of the prior art mixing devices are crude and imprecise making accurate, sterile and thorough mixing of the drug and the diluent difficult, time consuming and not well suited for use in the home environment.
Several types of closed drug delivery systems are presently in use. These systems typically comprise a flexible container such as a plastic bag to which a drug vial can be coupled. The flexible container usually contains a liquid diluent and often includes a frangible member that allows fluid passage only when broken. When the drug vial is coupled with the flexible container, the stopper of the drug vial is pierced and the frangible member ruptured so as to allow sterile communication between the drug vial and the liquid diluent contents of the flexible container. Mixing of the drug with the diluent is accomplished by manipulating the flexible container. Exemplary of prior art systems of the aforementioned character are those disclosed in U.S. Pat. No. 4,583,971 issued to Bocquet, et al. and in U.S. Pat. No. 4,606,734 issued to Larkin.
Another prior art closed delivery and mixing system is disclosed in U.S. Pat. No. 4,458,733 issued to Lyons. The Lyons apparatus includes a compressible chamber with a liquid component therein, the compressible chamber including gas-trapping and reservoir compartments in open communication. The gas trapping compartment can be connected to a container such as a drug vial having a mixing component therein. After a pathway between the vial and the gas trapping compartment is opened, mixing is accomplished through manipulation of the compressible chamber.
Another very successful prior art, dual container system is described in U.S. Pat. Nos. 4,614,267 issued to Larkin and 4,614,515 issued to Tripp and Larkin. In this system, a flexible diluent container includes a tubular port which provides means for securing thereto a stoppered medicament vial as well as a stopper removal means. The stopper removal means includes an engagement element, or extractor, which is attached to a removable cover and seals the inner end of the port. In use, as the vial is advanced into the tubular port, the vial stopper moves into engagement with the extractor which grips the stopper enabling it to be pulled from the vial as the cover is pulled from the port. Once the stopper has been removed from the vial, the contents of the vial can be dumped into the diluent in the bag and mixed therewith through manipulation of the bag.
The prior art devices of the character described in the preceding paragraphs typically use the traditional gravity flow method for infusion of the medicament mixture into the patient. Such a method is cumbersome, imprecise and typically requires bed confinement of the patient. Also, the flexible bag must be maintained in a substantially elevated position and periodic monitoring of the apparatus by the nurse or doctor is required to detect malfunctions of the infusion apparatus.
The apparatus of the present invention overcomes the drawbacks of the prior art by totally eliminating the need for a flexible bag, the cumbersome manipulative mixing of the medicaments using the flexible bag and the undesirable gravity infusion method which is typically followed when the flexible bag is used. As will be described in the paragraphs which follow, the apparatus of the present invention makes use of recently developed gas permeable elastomeric films and similar materials, which, in cooperation with a plate-like base define a fluid chamber that initially contains the first component, such as a diluent. Adjacent the base and in communication with the fluid chamber is a sterile coupling means for operably interconnecting a container such as a drug vial containing the second component. To enable controlled, sterile intermixing of the first and second components, the apparatus includes flow control means for controlling the flow of fluid through internal passageways which interconnect the fluid chamber and the drug vial.
The apparatus of the present invention is small, compact, easy to use and inexpensive to manufacture. The apparatus provides a sterile, closed delivery system which can readily be used by ambulatory patients and in home care envorinment. Connector elements are provided on the housing of the device which permits the apparatus to be conveniently affixed to the patient's clothing or to be strapped to the patients body.
The apparatus of the invention can be used with minimal professional assistance in an alternate health care environment, such as the home. By way of example, devices of the invention can be used for intermixing numerous medicaments with suitable diluents and for the continuous infusion of medicament mixtures such as antibiotics, analgesics, hormonal, anticoagulants, clot dissolvers, immuno suppressants, and like medicinal agents. Similarly, the apparatus can be used for I-V chemotherapy and can accurately deliver fluids to the patient in precisely the correct quantities and at extended microinfusion rates over time.